Year : 2003 | Volume
: 13 | Issue : 4 | Page : 447--448
Radiological quiz - obstetrics
R Madan, MK Narula, R Anand, V Kalra
Department of Radiology, Lady Hardinge Medical College And assoc. Smt.S.K.Hospital, New Delhi, India
M K Narula
Department of Radiology, LHMC & Assoc. S.K.Hospitals, New Delhi 110001
|How to cite this article:|
Madan R, Narula M K, Anand R, Kalra V. Radiological quiz - obstetrics.Indian J Radiol Imaging 2003;13:447-448
|How to cite this URL:|
Madan R, Narula M K, Anand R, Kalra V. Radiological quiz - obstetrics. Indian J Radiol Imaging [serial online] 2003 [cited 2020 Feb 23 ];13:447-448
Available from: http://www.ijri.org/text.asp?2003/13/4/447/37198
A twenty year old primigravida presented to us for a routine ultrasound scan at approximately 20 weeks gestation. The pregnancy had been uneventful so far. The prenatal scans are shown in [Figure 1],[Figure 2],[Figure 3] and [Figure 4].
What is your diagnosis?
CONJOINED TWINS - THORACO-OMPHALOPAGUS
Prenatal sonogram shows twin gestation The twins appear to be placed face to face [Figure 1] and joined ventrally from the upper thorax to the umbilicus [Figure 2]; constant relative position of the fetuses were noted with heads and other body parts persistently at the same level. A common pericardial sac is seen with some degree of cardiac fusion [Figure 3]. The liver also appears fused. There was no evidence of pelvic conjunction with evidence of two legs per twin; however sex of the fetuses could not be ascertained. A single placenta is seen on the anterior uterine wall and a single cord with four vessels (multivessel cord) is noted [Figure 4]. A sac containing the fetal intestines was seen outside the fused abdomen inferior to the insertion of the cord.
On the basis of these findings, the diagnosis of conjoined twins- thoraco-omphalopagus was made.
The patient underwent hysterotomy following a failed induction. Two conjoined female twins with a combined weight of 1500gms were extracted out as breech. The babies expired immediately after birth. The thorax and abdomen were fused and a bag filled with babies' intestines was seen outside the abdomen. A single placenta and a single umbilical cord with 4 vessels were confirmed. The parents refused a postmortem autopsy.
Conjoined twins are rare and the estimated prevalence varies from 1:50,000 to 1:20,000[l]; an increased prevalence of 1:14,000 to 1:25,000 is observed in parts of Southeast Asia and Africa .A female dominance on the order of 3:1 has been reported .Forty percent to 60% of conjoined twins are stillborn, and almost 35% of live births do not survive 24 hours .
Conjoined twins are monozygotic, monoamniotic, and monochorionic; there is failure of separation of the embryonic plate between 13 and 17 days gestation . Such twins are classified according to the most prominent site of connection: the thorax (thoracopagus), abdomen (omphalopagus), sacrum (pygopagus), pelvis (ischiopagus), skull (craniopagus), face (cephalopagus), or back (rachipagus).
The antenatal diagnosis can be made with ultrasonography (US) as early as 12 weeks gestation. More accurate evaluation of visceral conjunction is possible from 20 weeks gestation .
An imaging strategy to accurately define anatomic fusion, vascular anomalies, and associated abnormalities is important for surgical planning and prognostic information. , Accurate preoperative imaging aids in successful'; separation of conjoined twins. Higher frequencies of cardiac abnormalities have been reported in all forms of conjoined twinning. Conjoined hearts are easier to examine in utero because the amniotic fluid acts as a buffer during US. After birth, the lungs inflate with air and thoracic fusion prevents optimal access .
Magnetic resonance imaging and computed tomography provide excellent anatomic and bone detail, demonstrating organ position, shared viscera, and limited vascular anatomy. A shared liver requires evaluation of hepatic anatomy, hepatic vascularisation (angiography) and biliary drainage (using dynamic biliary scintigraphy with Tc-99m HIDA),. Contrast studies of upper gastro-intestinal tract are necessary in cases of thoraco-abdominal fusion, and studies of lower gastro-intestinal tract are necessary in cases of pelvic union .Angiography and vascular studies are important to evaluate crossover circulation to shared viscera, shunting of blood between twins and to define specific vascular supply to organs. Recently, ultrasound contrast agents (micro bubbles like SHU-508A) have been used to confirm interfetal transfusion in monochorionic twins and delineate placental angio architecture in cases of twin-twin transfusion .
The outcome is better in twins who do not share vital organs such as the heart or brain, and the best results are reported for omphalopagus twins and pygopagus twins without neural involvement,.
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